JP2016160456A - Copper-containing particle, conductor forming composition, method for producing conductor, conductor and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-containing particle that enables excellent formation of a conductor at a low temperature, a conductor forming composition comprising the copper-containing particle, a method for producing a conductor which can be performed at a low temperature, a conductor which can be produced at a low temperature, and a device comprising the conductor.SOLUTION: A copper-containing particle has a core particle comprising copper, and organic matter present in at least part of the surface of the core particle, where a percentage of copper-containing particles with a major axis length of 50 nm or less is 80% or less.SELECTED DRAWING: None

Description

  The present invention relates to copper-containing particles, a conductor-forming composition, a method for producing a conductor, a conductor, and an apparatus.

  As a method for forming a metal pattern, a step of applying a conductive material such as ink or paste containing metal particles such as copper onto a substrate by ink jet printing, screen printing, etc., and heating the conductive material to fuse the metal particles In addition, a so-called printed electronics method is known which includes a conductor-forming step for developing conductivity. As the metal particles contained in the conductive material, those in which an organic substance as a coating material is attached to the surface in order to suppress the oxidation of the metal and enhance the storage stability are known.

  Patent Document 1 describes a copper particle coated with an organic substance that can be fused at a low temperature and exhibits good conductivity, and a method for producing the same. The copper particles described in Patent Document 1 are obtained by mixing a copper precursor such as copper oxalate and a reducing compound such as hydrazine to obtain a composite compound, and heating the composite compound in the presence of an alkylamine. It is manufactured by the method which has these. In the example of Patent Document 1, the ink containing the produced copper particles is heated to 300 ° C. at 60 ° C./min in an argon atmosphere and held for 30 minutes to achieve the conductorization. Patent Document 2 describes a method for producing copper particles using fatty acid copper as a copper precursor in the method described in Patent Document 1. In the example of Patent Document 2, it is described that the obtained thin film of copper particles was made into a conductor by heating at 200 ° C.

JP 2012-72418 A JP 2014-148732 A

  In recent years, against the background of improvement in production efficiency and diversification of types of base materials to be used, development of a technology that enables fusion of metal particles at a lower temperature (for example, 150 ° C. or less) has been demanded. Therefore, development of metal particles that can be fused at a temperature lower than the temperatures described in Patent Document 1 and Patent Document 2 and a method for forming a conductor using the metal particles is required.

  In view of the above problems, the present invention provides a copper-containing particle having excellent conductorization ability at low temperature, a conductor-forming composition containing the copper-containing particle, a method for producing a conductor that can be carried out at low temperature, a conductor that can be produced at low temperature, and the above An object is to provide an apparatus including a conductor.

Means for solving the above problems are as follows.
<1> The ratio of copper-containing particles having core particles containing copper and an organic substance present on at least a part of the surface of the core particles and having a major axis length of 50 nm or less is 80% or less. Some copper-containing particles.
<2> The copper-containing particles according to <1>, wherein the ratio of the copper-containing particles having a major axis length of 70 nm or more is 20% or more.
<3> The copper-containing particles according to any one of <1> or <2>, wherein an average value of the lengths of the major axes is 40 nm or more.
<4> The copper-containing particles according to any one of <1> to <3>, wherein an average value of the lengths of the major axes is 300 nm or less.
<5> At least one of the first copper-containing particles having a major axis length of 5 nm to 50 nm or less, the major axis is longer than the first copper-containing particle, and the major axis length is 30 nm to 300 nm. The copper-containing particles according to any one of <1> to <4>, comprising composite particles formed from at least one of the second copper-containing particles.
<6> A conductor-forming composition comprising the copper-containing particles according to any one of <1> to <5> and a dispersion medium.
The manufacturing method of the conductor which has the process of heating the conductor formation composition as described in <7><6>.
<8> A conductor having a structure in which the copper-containing particles according to any one of <1> to <5> are fused.
<9> A device including the conductor according to <7>.

  According to the present invention, copper-containing particles having excellent conductorization ability at low temperature, a conductor-forming composition containing the copper-containing particles, a method for producing a conductor that can be carried out at low temperature, a conductor that can be produced at low temperature, and the conductor An apparatus can be provided.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless explicitly specified, unless otherwise clearly considered essential in principle. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the purpose of the process is achieved even when it cannot be clearly distinguished from other processes. In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In addition, in the present specification, the content of each component in the composition is such that when there are a plurality of substances corresponding to each component in the composition, the plurality of substances present in the composition unless otherwise specified. Means the total amount. In the present specification, the particle diameter of each component in the composition is such that when there are a plurality of particles corresponding to each component in the composition, the plurality of particles present in the composition unless otherwise specified. The value for a mixture of In this specification, the term “film” includes not only a configuration of a shape formed on the entire surface but also a configuration of a shape formed on a part when observed as a plan view.

  In the present specification, “conducting” means that metal-containing particles are fused to be changed into a conductor. The “conductor” refers to an object having conductivity, and more specifically, an object having a volume resistivity of 300 μΩ · cm or less. “Percent” means a percentage (percentage) based on the number.

<Copper-containing particles>
The copper-containing particles of the present invention have a core particle containing copper and an organic substance present on at least a part of the surface of the core particle, and the ratio of the copper-containing particles whose major axis length is 50 nm or less. 80% or less. In the present invention, the major axis of the copper-containing particles means a distance between two planes selected so that the distance between the two planes circumscribing the copper-containing particles and parallel to each other is maximized. In this specification, the ratio of the copper-containing particles having a major axis length of 50 nm or less is a ratio of the 200 copper-containing particles selected at random. For example, when the number of copper-containing particles having a major axis length of 50 nm or less is 160 in 200, the ratio of the copper-containing particles having a major axis length of 50 nm or less is 80%.

  Since the copper-containing particles of the present invention have the above-described configuration, they are excellent in conductorization ability at a low temperature (for example, 150 ° C.). That is, in the copper-containing particles of the present invention, an organic substance present on at least a part of the surface of the core particles containing copper serves as a protective material and suppresses oxidation of the core particles. For this reason, good fusion properties at low temperatures are maintained even after long-term storage in the atmosphere. In addition, this organic substance is thermally decomposed by heating when the conductor is produced by fusing the copper-containing particles and disappears.

  Furthermore, the copper-containing particles of the present invention have a conductorization ability at low temperatures because the ratio of copper-containing particles (hereinafter also referred to as small-diameter particles) having a major axis length of 50 nm or less is 80% or less. Are better.

  The reason why the ratio of the small-diameter particles in the copper-containing particles is 80% or less is not clear, but the present inventors consider as follows. Particles whose major axis in the copper-containing particles exceeds 50 nm (hereinafter also referred to as large-diameter particles) mainly have a conductive function, and small-sized particles whose major axis has a length of 50 nm or less are larger by melting. Responsible for forming a conductive path by bonding the diameter particles. When the number of small-diameter particles in the copper-containing particles is too large, the number of large-diameter particles is insufficient and a good conductor tends not to be formed. In the present invention, it is possible to form a good conductor at a low temperature because the ratio of the small-diameter particles in the copper-containing particles is within an appropriate range.

  Patent Document 1 and Patent Document 2 describe that the average particle diameter of copper particles is 50 nm or less, and further the average particle diameter is 20 nm. Patent Document 2 describes that copper particles having a particle diameter of 10 nm or less and copper particles having a particle diameter of 100 to 200 nm were mixed in the copper particles obtained in the examples. However, there is no specific description regarding the proportion of small-diameter particles in the entire copper particles in any of the patent documents, and there is no description suggesting the relationship between the proportion of small-diameter particles and the ability to make conductors.

  From the viewpoint of conductorization ability at low temperature, the proportion of copper-containing particles having a major axis length of 50 nm or less is preferably 75% or less, more preferably 70% or less, and 65 particles. % Or less is more preferable.

  From the viewpoint of conductorization ability at low temperature, the ratio of copper-containing particles having a major axis length of 50 nm or less is preferably 55% or more, more preferably 58% or more, and 60 % Or more is more preferable.

  From the viewpoint of conducting ability at low temperatures, the proportion of particles having a major axis length of 70 nm or more is preferably 20% or more, more preferably 30% or more, and 35% or more. More preferably. In this specification, the ratio of the copper-containing particles having a major axis length of 70 nm or more is a ratio of the 200 copper-containing particles selected at random.

  From the viewpoint of conducting ability at low temperatures, the average value of the length of the major axis is preferably 40 nm or more, more preferably 50 nm or more, further preferably 60 nm or more, and 80 nm or more. More preferably. In the present specification, the average value of the length of the long axis is an arithmetic average value of the length of the long axis measured for 200 copper-containing particles selected at random.

  From the viewpoint of conducting ability at low temperatures, the average value of the length of the major axis is preferably 300 nm or less, more preferably 200 nm or less, and further preferably 150 nm or less.

  From the viewpoint of conducting ability at low temperatures, the long axis length of the copper-containing particles having the longest long axis length (hereinafter also referred to as the maximum diameter particle) is preferably 350 nm or less, and 300 nm or less. More preferably, it is more preferably 250 nm or less. In this specification, the length of the major axis of the largest-diameter particle is the length of the major axis of the copper-containing particle having the longest longest length among the 200 copper-containing particles selected at random.

  From the viewpoint of conductorization ability at low temperature, the length of the major axis of the copper-containing particles (hereinafter also referred to as the smallest diameter particles) having the shortest major axis length among the randomly selected 200 particles Is preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more. In the present specification, the length of the long axis of the smallest diameter particle is the length of the long axis of the copper-containing particle having the shortest long axis length among the 200 copper-containing particles randomly selected.

  The length of the major axis of the copper-containing particles is adjusted, for example, by the conditions such as the type of raw materials, the temperature at the time of mixing the raw materials, the reaction time, the reaction temperature, the washing step, the washing solvent, etc. Can be done. The ratio of the small-diameter particles in the copper-containing particles may be adjusted by adjusting the above-described conditions, and two or more kinds of copper-containing particles having different particle diameters are separately produced and mixed at a desired ratio. It may be adjusted depending on the situation.

  From the viewpoint of promoting good conductorization at a low temperature, the copper-containing particles of the present invention contain at least one first copper-containing particle having a major axis length of 5 nm to 50 nm and the first copper-containing particles. It is preferable to include composite particles formed from at least one second copper-containing particle having a long axis longer than that of the particle and a length of the long axis of 30 nm to 300 nm.

  Although it is not clear why the copper-containing particles of the present invention contain composite particles and good conductorization at low temperature is promoted, the first copper-containing particles adhere to the second copper-containing particles, One factor is that the shape of the second copper-containing particles is more complicated than the shape of the second copper-containing particles alone, the melting point is lowered due to the so-called nanosize effect, and the fusion property at low temperature is promoted. Conceivable.

The shape of the composite particles is not particularly limited. For example, the circularity is preferably 0.70 to 0.99. The circularity is a value represented by 4π × S / (perimeter length) ² , S is the area of the measurement target particle, and the perimeter length is the perimeter length of the measurement target particle. The circularity can be obtained by analyzing an electron microscope image using image processing software.

  The shape of the copper-containing particles is not particularly limited and can be selected according to the application. For example, the aspect ratio that is the ratio of the major axis to the minor axis (major axis / minor axis) of the copper-containing particles can be selected from a range of 1.0 to 10.0. When a mixture of copper-containing particles and a dispersion medium or the like is applied to a substrate by a printing method, the average aspect ratio that is the ratio of the major axis to the minor axis (major axis / minor axis) of the copper-containing particles is 1. 0.5 to 8.0 is preferable because the viscosity of the mixture can be easily adjusted. The minor axis of the copper-containing particles means a distance between two planes selected so that a distance between two planes circumscribing the copper-containing particles and parallel to each other is minimized. The aspect ratio of the copper-containing particles can be examined by a usual method such as observation with an electron microscope.

  In an embodiment of the present invention, the average aspect ratio of 200 randomly selected particles is preferably 1.0 to 8.0, more preferably 1.1 to 6.0. Preferably, it is 1.2-3.0. In the present specification, the average value of the aspect ratio is obtained by respectively obtaining the arithmetic average value of the long axis and the arithmetic average value of the short axis of 200 randomly selected copper-containing particles, and the arithmetic average value of the obtained long axis. Is a value obtained by dividing by the arithmetic average value of the minor axis.

  The aspect ratio of the copper-containing particles can be performed, for example, by adjusting conditions such as the number of carbon atoms of the fatty acid used in the method for producing copper-containing particles described later.

  The length of the major axis of the copper-containing particles, the presence or absence of composite particles, the circularity, and the aspect ratio can be measured by a known method such as observation with an electron microscope. Although the magnification in the case of observing with an electron microscope is not specifically limited, For example, it can carry out by 20 times-50000 times. In addition, the copper containing particle | grains whose particle diameter is less than 3 nm are excluded from the object of a measurement.

  In an embodiment of the present invention, the organic substance present on at least a part of the surface of the core particle containing copper includes a substance derived from alkylamine. The presence of the organic substance and the alkylamine is confirmed by heating the copper-containing particles at a temperature equal to or higher than the temperature at which the organic substance is thermally decomposed in a nitrogen atmosphere and comparing the weights before and after the heating. As an alkylamine, the alkylamine used for the manufacturing method of the copper containing particle | grains mentioned later is mentioned.

  The proportion of the organic substance present on at least a part of the surface of the core particle is preferably 0.1% by mass to 20% by mass with respect to the total of the core particle and the organic substance. When the proportion of the organic substance is 0.1% by mass or more, sufficient oxidation resistance tends to be obtained. When the ratio of the organic substance is 20% by mass or less, the fusion property at a low temperature tends to be good. The ratio of the organic substance to the total of the core particles and the organic substance is more preferably 0.3% by mass to 10% by mass, and further preferably 0.5% by mass to 5% by mass.

  The core particles contain at least metallic copper, and may contain other substances as necessary. Examples of substances other than copper include metals such as gold, silver, platinum, tin, and nickel, or compounds containing these metal elements, fatty acid copper described later, organic compounds derived from reducing compounds or alkylamines, copper oxide, copper chloride, etc. Can be mentioned. From the viewpoint of forming a conductor having excellent conductivity, the content of metallic copper in the core particles is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more. Is more preferable.

  Since the organic substance is present on at least a part of the surface of the core particle, the copper-containing particles suppress copper oxidation even when stored in the air, and the oxide content is small. For example, in one embodiment, the content rate of the oxide in a copper containing particle is 5 mass% or less. The oxide content in the copper-containing particles can be measured by, for example, XRD (X-ray diffraction, X-ray diffraction).

<Method for producing copper-containing particles>
The method for producing the copper-containing particles is not particularly limited. For example, the copper-containing particles are produced by a method having a step of heating a composition containing a metal salt of a fatty acid and copper, a reducing compound, and an alkylamine. The method may include steps such as a centrifugation step and a washing step after the heating step as necessary.

  The said method uses the metal salt of a fatty acid and copper as a copper precursor. This makes it possible to use an alkylamine having a lower boiling point (that is, having a lower molecular weight) as a reaction medium than the method described in Patent Document 1 using silver oxalate or the like as a copper precursor. It is done. As a result, in the obtained copper-containing particles, organic substances present on the surface of the core particles are more likely to be thermally decomposed or volatilized, and it is considered easier to conduct the conductor at a low temperature.

(fatty acid)
The fatty acid is a monovalent carboxylic acid represented by RCOOH (R is a chained hydrocarbon group, which may be linear or branched). The fatty acid may be either a saturated fatty acid or an unsaturated fatty acid. From the viewpoint of efficiently covering the core particles and suppressing oxidation, linear saturated fatty acids are preferred. Only one type or two or more types of fatty acids may be used.

  The number of carbon atoms of the fatty acid is preferably 9 or less. Examples of saturated fatty acids having 9 or less carbon atoms include acetic acid (2 carbon atoms), propionic acid (3 carbon atoms), butyric acid and isobutyric acid (4 carbon atoms), valeric acid and isovaleric acid (5 carbon atoms), capron Examples include acids (carbon number 6), enanthic acid and isoenanthic acid (carbon number 7), caprylic acid, isocaprilic acid and isocaproic acid (carbon number 8), nonanoic acid and isononanoic acid (carbon number 9). Examples of the unsaturated fatty acid having 9 or less carbon atoms include those having one or more double bonds in the hydrocarbon group of the saturated fatty acid.

  The type of fatty acid can affect properties such as dispersibility of the copper-containing particles in the dispersion medium and fusing properties. For this reason, it is preferable to select the kind of fatty acid according to the use of copper-containing particles. From the viewpoint of homogenizing the particle shape, it is preferable to use a fatty acid having 5 to 9 carbon atoms and a fatty acid having 4 or less carbon atoms in combination. For example, nonanoic acid having 9 carbon atoms and acetic acid having 2 carbon atoms are preferably used in combination. The ratio in the case of using together the fatty acid having 5 to 9 carbon atoms and the fatty acid having 4 or less carbon atoms is not particularly limited.

  The method for obtaining a salt compound of fatty acid and copper (fatty acid copper) is not particularly limited. For example, it may be obtained by mixing copper hydroxide and a fatty acid in a solvent, or commercially available fatty acid copper may be used. Alternatively, by mixing copper hydroxide, a fatty acid and a reducing compound in a solvent, the formation of fatty acid copper and the formation of a complex formed between the fatty acid copper and the reducing compound are performed in the same process. Also good.

(Reducing compounds)
The reducing compound is considered to form a complex compound such as a complex between both compounds when mixed with fatty acid copper. As a result, the reducing compound becomes an electron donor to the copper ion in the fatty acid copper, the reduction of the copper ion is more likely to occur, and the liberation of copper atoms by spontaneous pyrolysis than the fatty acid copper in a state where no complex is formed. Is likely to occur. A reducing compound may be used individually by 1 type, or may use 2 or more types together.

  Specific examples of reducing compounds include hydrazine, hydrazine derivatives, hydrazine hydrochloride, hydrazine sulfate, hydrazine hydrate and other hydrazine compounds, hydroxylamine, hydroxylamine derivatives such as hydroxylamine compounds, sodium borohydride, sodium sulfite, hydrogen sulfite. Examples thereof include sodium compounds such as sodium, sodium thiosulfate, and sodium hypophosphite.

  A reducing compound having an amino group is preferable from the viewpoints of easily forming a coordination bond to a copper atom in fatty acid copper, and easily forming a complex while maintaining the structure of fatty acid copper. Examples of the reducing compound having an amino group include hydrazine and derivatives thereof, hydroxylamine and derivatives thereof, and the like.

  From the viewpoint of lowering the heating temperature (for example, 150 ° C. or lower) in the step of heating the composition containing fatty acid copper, the reducing compound and the alkylamine (hereinafter also referred to as the heating step), the evaporation or decomposition of the alkylamine occurs. It is preferable to select a reducing compound capable of forming a complex that causes reduction and liberation of a copper atom in a low temperature range. Examples of such reducing compounds include hydrazine and its derivatives, hydroxylamine and its derivatives, and the like. These reducing compounds can form a complex by forming a coordinate bond between a nitrogen atom constituting the skeleton and a copper atom. In addition, since these reducing compounds generally have a stronger reducing power than alkylamines, the resulting complexes tend to spontaneously decompose under relatively mild conditions, and tend to reduce and release copper atoms.

  By selecting a suitable one of these derivatives instead of hydrazine or hydroxylamine, the reactivity with the fatty acid copper can be adjusted, and a complex that generates spontaneous decomposition under a desired condition can be generated. Examples of hydrazine derivatives include methyl hydrazine, ethyl hydrazine, n-propyl hydrazine, isopropyl hydrazine, n-butyl hydrazine, isobutyl hydrazine, sec-butyl hydrazine, t-butyl hydrazine, n-pentyl hydrazine, isopentyl hydrazine, and neo-pentyl hydrazine. , T-pentylhydrazine, n-hexylhydrazine, isohexylhydrazine, n-heptylhydrazine, n-octylhydrazine, n-nonylhydrazine, n-decylhydrazine, n-undecylhydrazine, n-dodecylhydrazine, cyclohexylhydrazine, phenyl Examples include hydrazine, 4-methylphenylhydrazine, benzylhydrazine, 2-phenylethylhydrazine, 2-hydrazinoethanol, and acetohydrazine. Rukoto can. Examples of hydroxylamine derivatives include N, N-di (sulfoethyl) hydroxylamine, monomethylhydroxylamine, dimethylhydroxylamine, monoethylhydroxylamine, diethylhydroxylamine, N, N-di (carboxyethyl) hydroxylamine and the like. Can do.

  The ratio of the copper and the reducing compound contained in the fatty acid copper is not particularly limited as long as a desired complex is formed. For example, the ratio (copper: reducing compound) can be in the range of 1: 1 to 1: 4 on a molar basis, preferably in the range of 1: 1 to 1: 3, and 1: 1 to 1 : The range of 2 is more preferable.

(Alkylamine)
Alkylamine is considered to function as a reaction medium for a decomposition reaction of a complex formed from fatty acid copper and a reducing compound. Furthermore, it is considered that protons generated by the reducing action of the reducing compound are captured, and the reaction solution is inclined to be acidic and suppress the oxidation of copper atoms.

Alkylamine is a primary amine represented by RNH ₂ (R is a hydrocarbon group and may be cyclic or branched), R ₁ R ₂ NH (R ₁ and R ₂ are the same or different. Or a branched or branched hydrocarbon group), an alkylene diamine in which two amino groups are substituted on the hydrocarbon chain, and the like. The alkylamine may have one or more double bonds, and may have atoms such as oxygen, silicon, nitrogen, sulfur, and phosphorus. The alkylamine may be only one type or two or more types.

  The hydrocarbon group of the alkylamine preferably has 7 or less carbon atoms. When the carbon number of the hydrocarbon group of the alkylamine is 7 or less, the alkylamine tends to be thermally decomposed during heating for fusing the copper-containing particles to form a conductor, and a good conductor can be achieved. It is in. The hydrocarbon group of the alkylamine preferably has 6 or less carbon atoms, more preferably 3 or more carbon atoms.

  Specific examples of the primary amine include ethylamine, 2-ethoxyethylamine, propylamine, butylamine, isobutylamine, pentylamine, isopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, Examples include hexadecylamine, oleylamine, 3-methoxypropylamine, and 3-ethoxypropylamine.

  Specific examples of the secondary amine include diethylamine, dipropylamine, dibutylamine, ethylpropylamine, ethylpentylamine, dibutylamine, dipentylamine, and dihexylamine.

  Specific examples of alkylenediamine include ethylenediamine, N, N-dimethylethylenediamine, N, N′-dimethylethylenediamine, N, N-diethylethylenediamine, N, N′-diethylethylenediamine, 1,3-propanediamine, 2,2 -Dimethyl-1,3-propanediamine, N, N-dimethyl-1,3-diaminopropane, N, N'-dimethyl-1,3-diaminopropane, N, N-diethyl-1,3-diaminopropane, 1,4-diaminobutane, 1,5-diamino-2-methylpentane, 1,6-diaminohexane, N, N′-dimethyl-1,6-diaminohexane, 1,7-diaminoheptane, 1, Examples thereof include 8-diaminooctane, 1,9-diaminononane, 1,12-diaminododecane and the like.

  The alkylamine preferably contains at least one alkylamine whose hydrocarbon group has 7 or less carbon atoms. Thereby, the copper containing particle | grains which are excellent by the melt | fusion property in low temperature can be manufactured. Alkylamines may be used alone or in combination of two or more. The alkylamine may include an alkylamine having a hydrocarbon group having 7 or less carbon atoms and an alkylamine having a hydrocarbon group having 8 or more carbon atoms. When an alkylamine having a hydrocarbon group having 7 or less carbon atoms and an alkylamine having 8 or more carbon atoms in a hydrocarbon group are used in combination, the alkylamine having a hydrocarbon group having 7 or less carbon atoms in the entire alkylamine Is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more.

  The ratio of copper and alkylamine contained in fatty acid copper is not particularly limited as long as desired copper-containing particles are obtained. For example, the ratio (copper: alkylamine) can be in a range of 1: 1 to 1: 8 on a molar basis, preferably in a range of 1: 1 to 1: 6, and 1: 1 to 1: A range of 4 is more preferable.

(Heating process)
The method for carrying out the step of heating the composition containing fatty acid copper, reducing compound and alkylamine is not particularly limited. For example, a method in which fatty acid copper and a reducing compound are mixed in a solvent and then heated by adding an alkylamine, a method in which fatty acid copper and an alkylamine are mixed in a solvent and then further heated by adding a reducing compound, a fatty acid A method of heating copper hydroxide, a fatty acid, a reducing compound, and an alkylamine, which are copper starting materials, in a solvent, a method of heating, a method of mixing a fatty acid copper and an alkylamine in a solvent, and then adding a reducing compound and heating Etc.

  The heating step can be performed at a relatively low temperature by using fatty acid copper having 9 or less carbon atoms as a copper precursor. For example, it can be performed at 150 ° C. or lower, preferably 130 ° C. or lower, more preferably 100 ° C. or lower.

  The composition containing fatty acid copper, a reducing compound and an alkylamine may further contain a solvent. From the viewpoint of promoting the formation of a complex of fatty acid copper and a reducing compound, it is preferable to include a polar solvent. Here, the polar solvent means a solvent that dissolves in water at 25 ° C., and is preferably an alcohol. Use of alcohol tends to promote complex formation. Although the reason is not clear, it is considered that contact with a water-soluble reducing compound is promoted while dissolving fatty acid copper which is a solid. A solvent may be used individually by 1 type, or may use 2 or more types together.

  As alcohol which melt | dissolves in water at 25 degreeC, C1-C8 can be mentioned and the alcohol which has one hydroxyl group in a molecule | numerator can be mentioned. Examples of such alcohols include linear alkyl alcohols, phenols, and those obtained by replacing hydrogen atoms of hydrocarbons having an ether bond in the molecule with hydroxyl groups. From the viewpoint of expressing a stronger polarity, an alcohol having two or more hydroxyl groups in the molecule is also preferably used. Moreover, you may use alcohol containing a sulfur atom, a phosphorus atom, a silicon atom, etc. according to the use of the copper containing particle | grains manufactured.

  Specific examples of alcohol include methanol, ethanol, 1-propanol, 2-propanol, butanol, pentanol, hexanol, heptanol, octanol, allyl alcohol, benzyl alcohol, pinacol, propylene glycol, menthol, catechol, hydroquinone, salicyl alcohol, Examples thereof include glycerin, pentaerythritol, sucrose, glucose, xylitol, methoxyethanol, triethylene glycol monomethyl ether, ethylene glycol, triethylene glycol, tetraethylene glycol, and pentaethylene glycol.

  Among alcohols, methanol, ethanol, 1-propanol and 2-propanol having a very high solubility in water are preferable, 1-propanol and 2-propanol are more preferable, and 1-propanol is still more preferable.

<Conductor-forming composition>
The conductor-forming composition of the present invention contains the copper-containing particles of the present invention and a dispersion medium. Since the conductor-forming composition of the present invention contains the copper-containing particles of the present invention that are excellent in conductorizing ability at low temperatures, it can be made into a conductor at low temperatures. Examples of the conductor forming composition include conductive paints, conductive pastes, and conductive inks.

  The shape of the copper-containing particles contained in the conductor-forming composition is not particularly limited. Specific examples include a spherical shape, a long granular shape, a flat shape, a fibrous shape, and the like, which can be selected according to the use of the copper-containing particles. When the conductor-forming composition is applied to a printing method, the shape of the copper-containing particles is preferably spherical or long granular.

  The type of the dispersion medium is not particularly limited, and can be selected from organic solvents that are generally used according to the use of the conductor-forming composition, and can be used alone or in combination of two or more. When the conductor-forming composition is applied to the printing method, it contains at least one selected from the group consisting of terpineol, isobornylcyclohexanol, dihydroterpineol and dihydroterpineol acetate from the viewpoint of controlling the viscosity of the conductor-forming composition. It is preferable.

  The viscosity of the conductor-forming composition is not particularly limited and can be selected according to the method of using the conductor-forming composition. For example, when the conductor-forming composition is applied to the screen printing method, the viscosity is preferably 0.1 Pa · s to 30 Pa · s, and more preferably 1 Pa · s to 30 Pa · s. When the conductor-forming composition is applied to the inkjet printing method, the viscosity is preferably 0.1 mPa · s to 30 mPa · s, although it depends on the standard of the inkjet head to be used, and is 5 mPa · s to 20 mPa · s. More preferably.

  The conductor-forming composition may contain components other than the copper-containing particles and the dispersion medium as necessary. Examples of such components include silane coupling agents, polymer compounds, radical initiators, reducing agents, and the like.

<Manufacturing method of conductor>
The manufacturing method of the conductor of this invention has the process (heating process) of heating the conductor formation composition of this invention. In the heating step, the organic matter on the surface of the copper-containing particles contained in the conductor-forming composition is thermally decomposed and the copper-containing particles are fused. Since the conductor-forming composition of the present invention can be made into a conductor at a low temperature, the heating step can be performed at a temperature of 200 ° C. or lower, preferably 150 ° C. or lower.

  The components in the atmosphere in which the heating process is performed are not particularly limited, and can be selected from nitrogen, argon, and the like used in a normal conductor manufacturing process. Further, a reducing substance such as hydrogen or formic acid may be heated in an atmosphere saturated with nitrogen or the like. The pressure during heating is not particularly limited, but by reducing the pressure, conductorization at a lower temperature tends to be promoted.

  The heating process may be performed at a constant rate of temperature rise or may be changed irregularly. The time for the heating step is not particularly limited, and can be selected in consideration of the heating temperature, the heating atmosphere, the amount of copper-containing particles, and the like. The heating method is not particularly limited, and examples thereof include heating with a hot plate, heating with an infrared heater, and heating with a pulse laser.

  The conductor manufacturing method may have other steps as necessary. Other steps include a step of applying the conductor-forming composition to the substrate before the heating step, a step of removing at least a part of the volatile components in the conductor-forming composition by the drying before the heating step, and a reduction after the heating step. Examples thereof include a step of reducing copper oxide generated by heating in an atmosphere, a step of performing light baking after the heating step to remove residual components, and a step of applying a load to the conductor obtained after the heating step.

<Conductor>
The conductor of the present invention has a structure in which the copper-containing particles of the present invention are fused. The shape of the conductor is not particularly limited, and examples thereof include a thin film shape and a pattern shape. The conductor of the present invention can be used for forming wirings, coatings and the like for various electronic components. In particular, since the conductor of the present invention can be produced at a low temperature, it is suitably used for applications in which a metal foil, a wiring pattern or the like is formed on a substrate having low heat resistance such as a resin. Further, it is also suitably used for applications such as decoration and printing not intended for energization.

  When a conductor-forming composition is applied on a substrate and heated to form a conductor, the material of the substrate is not particularly limited and may or may not have conductivity. Specifically, metals such as Cu, Au, Pt, Pd, Ag, Zn, Ni, Co, Fe, Al, Sn, alloys of these metals, semiconductors such as ITO, ZnO, SnO, Si, glass, graphite, Examples thereof include carbon materials such as graphite, resin, paper, and combinations thereof. Since the conductor of the present invention can be obtained by heating at a low temperature, it can be suitably applied particularly when a substrate made of a material having relatively low heat resistance is used. A thermoplastic resin is mentioned as a material with comparatively low heat resistance. Examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene, and polycarbonate resins. The shape of the substrate is not particularly limited, and may be a plate shape, a rod shape, a roll shape, a film shape, or the like.

  The volume resistivity of the conductor is preferably 200 μΩ · cm or less, more preferably 100 μΩ · cm or less, still more preferably 50 μΩ · cm or less, and particularly preferably 25 μΩ · cm or less.

  The conductor of the present invention can be used for various applications. Specifically, it can be used as a member such as an electric wiring, a heat dissipation film, or a surface coating film used for electronic parts such as a laminated plate, a solar cell panel, a display, a transistor, and a semiconductor package. In particular, since the conductor contained in the apparatus of the present invention can be formed on a substrate such as a resin, it is suitable for the production of flexible laminates, solar cell panels, displays and the like.

<Device>
The apparatus of the present invention includes the conductor of the present invention. The type of device is not particularly limited. For example, electronic components such as a wiring board made of the conductor of the present invention, a laminate having a coating film, a solar battery panel, a display, a transistor, and a semiconductor package can be used. In addition, electronic devices, home appliances, industrial machines, transport machines, and the like that incorporate these electronic components are also included in the apparatus of the present invention.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples at all.

<Example 1>
[1.1] Synthesis of copper nonanoate To 91.5 g (0.94 mol) of copper hydroxide (Kanto Chemical Co., Ltd., special grade), 150 mL of 1-propanol (Kanto Chemical Co., Ltd., special grade) was added and stirred. 370.9 g (2.34 mol) of nonanoic acid (Kanto Chemical Co., Inc., 90% or more) was added. The obtained mixture was heated and stirred at 90 ° C. for 30 minutes in a separable flask. The obtained solution was filtered while heated to remove undissolved substances. Thereafter, the mixture was allowed to cool, and the produced copper nonanoate was suction filtered and washed with hexane until the washing liquid became transparent. The obtained powder was dried in an explosion-proof oven at 50 ° C. for 3 hours to obtain copper (II) nonanoate. The yield was 340 g (yield 96 mass%).

[1.2] Synthesis of copper-containing particles (large diameter particles) 15.01 g (0.040 mol) of copper nonate (II) obtained above and copper (II) acetate anhydride (Kanto Chemical Co., Ltd., special grade) 7.21 g (0.040 mol) is put in a separable flask, 10 mL of 1-propanol and 32.1 g (0.32 mol) of hexylamine (Tokyo Chemical Industry Co., Ltd., purity 99%) are added, and 80 in an oil bath. It was heated and stirred at 0 ° C. to dissolve. After transferring to an ice bath and cooling to an internal temperature of 5 ° C., a solution obtained by dissolving 7.72 mL (0.16 mol) of hydrazine monohydrate (Kanto Chemical Co., Ltd., special grade) in 12 mL of 1-propanol Added to the copper solution and stirred in an ice bath. The molar ratio of copper: hexylamine is 1: 4. Subsequently, it heated and stirred at 90 degreeC in the oil bath. At that time, the reduction reaction accompanied with foaming proceeded, and the reaction was completed within 30 minutes. The inner wall of the separable flask had a copper luster and the solution turned dark red. Centrifugation was performed at 9000 rpm (rotation / min) for 1 minute to obtain a solid. The step of further washing the solid with 15 mL of hexane was repeated three times to remove the acid residue, thereby obtaining a copper cake A containing a powder of copper-containing particles having copper luster.

  When copper-containing particles in copper cake A were observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F), the average value of the major axes of 200 copper-containing particles randomly selected Is 150 nm, the proportion of copper-containing particles having a major axis length of 50 nm or less is 30%, the proportion of copper-containing particles having a major axis length of 70 nm or more is 60%, The long axis of the diameter particle was 200 nm, and the average aspect ratio was 1.2.

[1.3] Synthesis of copper-containing particles (small-diameter particles) Powder of copper-containing particles having copper luster in the same manner as in [1.2] except that the reduction reaction with foaming was completed within 10 minutes. A copper cake B containing was obtained.

  When copper-containing particles in copper cake B were observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F), the average value of the major axes of 200 copper-containing particles randomly selected Is 20 nm, the proportion of copper-containing particles having a major axis length of 50 nm or less is 90%, the proportion of copper-containing particles having a major axis length of 70 nm or more is 5%, and the maximum The major axis length of the diameter particles was 80 nm, and the average aspect ratio was 1.2.

  Copper cake A (30 parts by mass), copper cake B (30 parts by mass) terpineol (20 parts by mass), and isobornylcyclohexanol (trade name: Tersolve MTPH, Nippon Terpene Chemical Co., Ltd.) (20 parts by mass) are mixed. Thus, a conductive composition was prepared. The obtained electroconductive composition was apply | coated on the polyethylene naphthalate (PEN) film, and it heated and formed the thin film of metallic copper. Heating was performed by holding at 140 ° C. for 60 minutes in an oven with a pressure of 500 Pa nitrogen atmosphere.

  When the copper-containing particles in the conductive composition were observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F), the long axis average of 200 copper-containing particles randomly selected The value is 85 nm, the ratio of copper-containing particles having a major axis length of 50 nm or less is 60%, the ratio of copper-containing particles having a major axis length of 70 nm or more is 33%, and the maximum The long axis of the diameter particle was 200 nm, and the average aspect ratio was 1.2.

<Comparative Example 1>
The copper cake B (60 parts by mass), terpineol (20 parts by mass), and isobornylcyclohexanol (trade name: Tersolve MTPH, Nippon Terpene Chemical Co., Ltd.) (20 parts by mass) are mixed to obtain a conductive composition. Prepared. The obtained electroconductive composition was apply | coated on the polyethylene naphthalate (PEN) film, and it heated and formed the thin film of metallic copper. Heating was performed by holding at 140 ° C. for 60 minutes in an oven with a pressure of 500 Pa nitrogen atmosphere.

(Evaluation)
The surface resistivity measured by a four-end needle surface resistance measuring instrument and the volume resistivity of the metallic copper thin film obtained in each example and each comparative example, and a non-contact surface / layer cross-sectional shape measurement system (VertScan, Inc.) Table 1 shows the results calculated from the film thickness obtained by Ryoka System.

<Example 2>
Copper cake A (10 parts by mass), copper cake B (30 parts by mass) terpineol (13.3 parts by mass), and isobornylcyclohexanol (trade name: Tersolve MTPH, Nippon Terpene Chemical Co., Ltd.) (13.3 parts by mass) Part) was mixed to prepare a conductive composition. The obtained electroconductive composition was apply | coated on the polyethylene naphthalate (PEN) film, and it heated and formed the thin film of metallic copper. Heating was performed by holding at 140 ° C. for 60 minutes in an oven with a pressure of 500 Pa nitrogen atmosphere.

  When the copper-containing particles in the conductive composition were observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-2100F), the long axis average of 200 copper-containing particles randomly selected The value is 52 nm, the ratio of copper-containing particles having a major axis length of 50 nm or less is 75%, the ratio of copper-containing particles having a major axis length of 70 nm or more is 23%, and the maximum The long axis of the diameter particle was 200 nm, and the average aspect ratio was 1.2.

  From the above, it can be seen that according to the conductive composition of the present invention, a conductor having excellent conductivity can be formed by low-temperature treatment at 150 ° C. or lower.

Claims (9)

  A copper-containing core particle containing copper and an organic substance present on at least a part of the surface of the core particle, wherein the ratio of copper-containing particles having a major axis length of 50 nm or less is 80% or less particle.   The copper-containing particles according to claim 1, wherein the ratio of copper-containing particles having a major axis length of 70 nm or more is 20% or more.   The average value of the length of a long axis is 40 nm or more, The copper content particle according to any one of claims 1 or 2.   The average value of the length of a long axis is 300 nm or less, The copper containing particle | grains of any one of Claims 1-3.   At least one first copper-containing particle having a major axis length of 5 nm to 50 nm or less, a major axis longer than the first copper-containing particle, and a major axis length of 30 nm to 300 nm. The copper-containing particle according to any one of claims 1 to 4, comprising composite particles formed from at least one of the two copper-containing particles.   The conductor formation composition containing the copper containing particle | grains of any one of Claims 1-5, and a dispersion medium.   The manufacturing method of the conductor which has the process of heating the conductor formation composition of Claim 6.   A conductor having a structure in which the copper-containing particles according to claim 1 are fused.   An apparatus comprising the conductor of claim 7.